The Lateral Geniculate Nucleus (LGN) is a major stage in the central visual pathway of higher animals. Its elaborate laminated structure, variety of cell types and synaptic contacts, together with major non-retinal inputs from many brain structures strongly indicate that it fulfils an important role in the processing of visual information. However, that role is still largely elusive. In this project I propose to study the transfer of temporal and spatial information from retinal ganglion cells to the primary relay cells in the LGN of cats and macaque monkeys. With one electrode I will record simultaneously the synaptic (S) potentials elicited in the LGN cell by an action potential in the retinal ganglion cell, together with the spikes fired by the target LGN cell. I will investigate the following: 1) How does the transfer of information depend on the stimulus parameters (temporal and spatial frequencies, contrast, color)? 2) What role do other, non-retinal inputs to the LGN play in determining the filtering of the incoming information? 3) With intracellular recordings in the LGN I will study the cellular mechanisms which underlie the information processing in the LGN. The similarity of the macaque visual system to that of man makes the study important for the understanding of information processing in man.